Observation: Public

Observation Details

Signs of Unstable Snow

Observations

HN24 15cm w 25-30cm of snow since the 24th. Above 6,000ft the height of snow averaged 200cm. Near treeline, the Jan 26th wind event was from locally S-SW with light drifting, which had been covered by snow in the past 24hrs.

We experience multiple (4-5) large collapses above 6,200ft on either flat or polar NW-NE aspects. One was 20ft in diameter and another had cracks propagating 10ft. These were all in open terrain and some had sparse rocks or trees or were on typically wind-scoured features. Where we investigated, the culprit was a thick layer of mid-Jan facets (1.0-2.0mm) ↓40cm from the surface, above the Jan 12/13th rain crust.

We targetted slopes above 6,000ft for the Jan 24th facets/surface hoar and mid-Jan crust/facet sandwiches. We found the Jan 24th facets up to 1.0mm on most slopes accompanied by surface hoar on sheltered slopes. Where we traveled, the recent snow lacked enough cohesion to test the Jan 24th facets for propagation. On a sun-exposed west aspect at 6,200ft all of the mid-Jan crusts were merged into a strong, stout layer lacking any facets other than the Jan 24th. On flat terrain and slopes with a northerly tilt, the crusts (up to 4) were separated, sometimes eroding and friable, with facets sandwiched between.